Hey there, I have a problem with @OptIn annotation...

# multiplatform

[markizdeviler]

Hey there, I have a problem with @OptIn annotation. Here is a sample code below:
// commonMain

expect interface TestCallback

// iosMain

@OptIn(ExperimentalForeignApi::class)
actual typealias TestCallback = TestDelegateProtocol

There is a problem if I use TestCallback in commonMain package, it says: error: This declaration needs opt-in. Its usage must be marked with '@kotlinx.cinterop.ExperimentalForeignApi' or '@OptIn(kotlinx.cinterop.ExperimentalForeignApi::class)'

At first, for @OptIn annotated types (classes, properties...), Its usages are not required to opt into that API (ExperimentalForeignApi)
The second ExperimentalForeignApi is platform-specific, which means I can't use it on commonMain package.

Does anybody have this kind of problem?

[markizdeviler]

I assume that was a dumb question _)
As long as typealias uses cInterop generated class, that needs to be annotated. The misunderstanding part is the useless @OptIn annotation in this case.

My hotfix is to wrap an object to the interface and use this interface instead. So typealias itself should not be annotated.

interface TestDelegateProtocolProvider {
    @OptIn(ExperimentalForeignApi::class)
    fun provide(): TestDelegateProtocol
}